A solubility contains one mole each of HA and HB (both are weak acids) in one litre solution. Now 1 mole of NaOH is added to this solution so that both the acids are partly neutralised. Heat of neutralisation for HA and HB are- `11.8` and- `12.4` kcal respectively and the heat produced during partial neutralisation of HA and HB is- `12.25` kcal.
The ratio of dissociation constant of two acids are:

Options

A. `1:9`
B. `1:6`
C. `1:3`
D. `1:1`

Answer

A

Explanation

In solution` [HA] "left" = 0.75M` and `[HB] "left" = 0.25M` and `[A^(-)]` form `NaA= 0.25, [B^(-)]` from `NaB = 0.75`
Now, for `HA: K_(1) = ([H^(+)][A^(-)])/([HA])`
For `HB: K_(2)= ([H^(+)][B^(-)])/(HB]`
`:. (K_(1))/(K_(2))= ([A^(-)][HB])/([B^(-)][HA])= (0.25xx0.25)/(0.75xx0.75) = (1)/(9)`